Hi daysuki,
Thanks for reaching out here in the Apple Support Communities. I understand your microphone isn't working on your iPhone 7 Plus for phone calls or for video chats.
I'm glad to help with this.
You've done some great troubleshooting already.
I suggest you also test the microphone using Voice Memos, and using the Camera app for both the front and rear cameras.
This explains how: If the microphones on your iPhone, iPad, and iPod touch aren't working - Apple Support
If the microphone is grayed out in Voice Memos or the speaker is grayed out during phone calls, I recommend that you contact Apple Support to see about service options. You can use this link: Official Apple Support
Best Regards.